The largest and best organised fortification project in the Mediterranean, is the Venetian Walls in Heraklion, created for the protection of Chandakas (this is what Heraklion was called during the second Byzantine period) and they encompass "Old Heraklion city"
They started being built in 1462 and did not finish until about 100 years later, while they were a sample of advanced fortification. Built with durable materials, they were strong enough to withstand the 20-year siege by the Ottoman Empire army.
The way they look today is the result of novel designing back in the 16th century, with the surrounding stronghold being nearly 7km, in a triangle shape with the base towards the sea, the latter being in fact a kind of a mound.
There were 7 bastions in total (Sambionera, Vitouri, Jesus, Martinego, Bethlehem, Pantokrator, St. Andrews) in the shape of a heart and 4 gates (Molos, St. George or Lazareto, Jesus, Pantokrator).